Semiconductor package and manufacturing method thereof

ABSTRACT

A manufacturing method of a semiconductor package includes the following steps. A chip is provided. The chip has an active surface and a rear surface opposite to the active surface. The chip includes conductive pads disposed at the active surface. A first solder-containing alloy layer is formed on the rear surface of the chip. A second solder-containing alloy layer is formed on a surface and at a location where the chip is to be attached. The chip is mounted to the surface and the first solder-containing alloy layer is aligned with the second solder-containing alloy layer. A reflow step is performed on the first and second solder-containing alloy layers to form a joint alloy layer between the chip and the surface.

CROSS-REFERENCE

This application is a divisional application of and claims the priority benefit of U.S. patent application Ser. No. 16/116,892, filed on Aug. 29, 2018, now allowed. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Semiconductor devices and integrated circuits used in a variety of electronic applications, such as cell phones and other mobile electronic equipment, are typically manufactured from a single semiconductor wafer. The dies of the wafer may be processed and packaged with other semiconductor devices or dies at the wafer level, and various technologies have been developed for wafer level packaging. In addition, for multi-die packages, the arrangement of the dies and the corresponding connecting elements affects data transmission speed among semiconductor dies and reliability of the packaged products.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

FIG. 1A through FIG. 1Q show schematic cross-sectional views of structures produced at various stages of a manufacturing method of a semiconductor package according to some embodiments of the present disclosure.

FIG. 1R shows a schematic cross-sectional view of a semiconductor package connected to a circuit substrate according to some embodiments of the present disclosure.

FIG. 2A through FIG. 2D are schematic bottom views of structures produced at various stages of a manufacturing method of a semiconductor package according to some embodiments of the present disclosure.

FIG. 3A and FIG. 3B are schematic top views of a structure produced at various stages of a manufacturing method of a semiconductor package according to some embodiments of the present disclosure.

FIG. 4A through FIG. 4B are schematic cross-sectional views illustrating semiconductor packages according to some embodiments of the present disclosure.

FIG. 5A through FIG. 5G are schematic cross-sectional views illustrating structures produced at various stages of a manufacturing method of a semiconductor package according to some embodiments of the present disclosure.

FIG. 6 is a schematic cross-sectional view illustrating a semiconductor package according to some embodiments of the present disclosure.

DESCRIPTION OF THE EMBODIMENTS

The following disclosure provides many different embodiments or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

Other features and processes may also be included. For example, testing structures may be included to aid in the verification testing of the 3D packaging or 3DIC devices. The testing structures may include, for example, test pads formed in a redistribution layer or on a substrate that allows the testing of the 3D packaging or 3DIC, the use of probes and/or probe cards, and the like. The verification testing may be performed on intermediate structures as well as the final structure. Additionally, the structures and methods disclosed herein may be used in conjunction with testing methodologies that incorporate intermediate verification of known good dies to increase the yield and decrease costs.

Embodiments of the present disclosure describe the exemplary manufacturing process of package structures and the package structures fabricated there-from. Certain embodiments of the present disclosure are related to the package structures formed with aligning structures and bridging structures connecting dies. The wafers or dies may include one or more types of integrated circuits or electrical components on a bulk semiconductor substrate or a silicon/germanium-on-insulator substrate. The embodiments are intended to provide further explanations but are not to be used to limit the scope of the present disclosure.

FIG. 1A through FIG. 1R show schematic cross-sectional views illustrating structures produced at various stages of a manufacturing method of a semiconductor package 10 shown in FIG. 1R. Referring to FIG. 1A, a semiconductor wafer 100 is provided. In some embodiments, the semiconductor wafer 100 may be a silicon bulk wafer. In some embodiments, the semiconductor wafer 100 may be a wafer made of semiconductor materials, such as semiconductor materials of the groups III-V of the periodic table. In some embodiments, the semiconductor wafer 100 may include elementary semiconductor materials such as silicon or germanium, compound semiconductor materials such as silicon carbide, gallium arsenic, indium arsenide, or indium phosphide or alloy semiconductor materials such as silicon germanium, silicon germanium carbide, gallium arsenic phosphide, or gallium indium phosphide. The semiconductor wafer 100 has a plurality of semiconductor dies 110 formed therein, and the dies 110 are parts of the semiconductor wafer 100 defined by the cut lines C1-C1. The semiconductor wafer 100 includes a semiconductor substrate 112, a plurality of conductive pads 114 on a frontside surface 100 a of the semiconductor wafer 100 and a passivation layer 116 covering the frontside surface 100 a of the semiconductor wafer 100. In some embodiments, three dies are shown to represent plural dies of the wafer, but the number of the dies in the wafer is not limited by the embodiments. For each of the semiconductor dies 110, the semiconductor die 110 may include active components (e.g., transistors or the like) and, optionally, passive components (e.g., resistors, capacitors, inductors, or the like) formed in the semiconductor substrate 112. Each of the semiconductor dies 110 may be or include a logic die, such as a central processing unit (CPU) die, a graphic processing unit (GPU) die, a micro control unit (MCU) die, an input-output (I/O) die, a baseband (BB) die, or an application processor (AP) die. In some embodiments, the semiconductor die 110 includes a memory die such as high bandwidth memory die.

Each die 110 may present a plurality of conductive pads 114 formed on an active surface (top surface) 110 a of each die 110. Each top surface 110 a may correspond to a portion of the frontside surface 100 a of the semiconductor wafer 100. In certain embodiments, the conductive pads 114 include aluminum pads, copper pads, or other suitable metal pads. The passivation layer 116 extends over the frontside surface 100 a of the semiconductor wafer 100, and the passivation layer 116 is formed with openings revealing the conductive pads 114. In some embodiments, the passivation layer 116 may be a single layer or a multi-layered structure, including a silicon oxide layer, a silicon nitride layer, a silicon oxy-nitride layer, a dielectric layer formed by other suitable dielectric materials or combinations thereof. The conductive pads 114 may be partially exposed by the openings of the passivation layer 116. In some embodiments, the semiconductor wafer 100 includes a plurality of first conductive vias 210 and a plurality of second conductive vias 220 formed on the conductive pads 114, through the openings of the passivation layer 116 and electrically connected with the conductive pads 114. In some embodiments, the material of the first conductive vias 210 and the second conductive vias 220 includes copper, copper alloys, or other conductive materials, and may be formed by deposition, plating, or other suitable techniques. In some embodiments, the formation of the first and second conductive vias 210, 220 includes forming one or more sacrificial masks (not shown) having a plurality of openings exposing the conductive pads 114, filling the openings with a conductive material (not shown) and removing the sacrificial masks to obtain the conductive vias 210 and 220. In some embodiments, the first conductive vias 210 and the second conductive vias 220 are formed with different heights. In some embodiments, a height H₂₁₀ of the conductive vias 210 may be less than a height H₂₂₀ of the conductive vias 220. In some embodiments, the design of different via pattern densities may lead to a height difference between the conductive vias 210 and 220. For example, regions of the masks with denser opening patterns (openings with tight spacing there-between) may result in shorter first conductive vias 210 than other regions of the masks with loosely arranged openings. In some alternative embodiments, the first conductive vias 210 and the second conductive vias 220 may be formed with the same height, and the second conductive vias 220 may be further elongated by selective deposition, thereby resulting in a height difference between the second conductive vias 220 and the first conductive vias 210. In some other alternative embodiments, rather than elongating the second conductive vias 220, the first conductive vias 210 are shortened, for example, by performing an etching step in the presence of an auxiliary mask (not shown) that shields the second conductive vias 220. Choice of a method to generate the height difference between the first 210 and second 220 conductive vias may be dictated by consideration such as overall cost of the process and the type of application intended for the dies. In any case, the method chosen to produce a difference in height between the first conductive vias 210 and the second conductive vias 220, or even the existence of a difference in height, are not to be construed as a limitation of the present disclosure. In the embodiments where a difference in height exists between the first conductive vias 210 and the second conductive vias 220, the height H₂₁₀ of the first conductive vias 210 may be in the range from 5 μm to 10 μm, and the height H₂₂₀ of the second conductive vias 220 may be in the range from 50 μm to 60 μm. However, the disclosure is not limited by the heights H₂₁₀, H₂₂₀ of the first 210 and second 220 conductive vias, as the heights H₂₁₀, H₂₂₀ may be adjusted according to the design or production requirements. In some alternative embodiments, the heights H₂₁₀, H₂₂₀ of the conductive vias 210 and 220 may be the same.

In some embodiments, the semiconductor wafer 100 is overturned and placed onto a temporary carrier TC1, as shown in FIG. 1B, and the conductive vias 210, 220 are embedded in a protective glue G formed on the carrier TC1. In FIG. 1B, the protective glue G may completely cover the conductive vias 210, 220 and be disposed between the semiconductor wafer 100 and the temporary carrier TC1. In some embodiments, the protective glue G may be a temporary bonding material and the protective glue G may include a light-to-heat conversion (LTHC) release layer for aiding the removal of the temporary carrier TC1 in the subsequent processes. In some embodiments, the temporary carrier TC1 is a glass substrate, a metal plate, a plastic supporting board or the like, but other suitable substrate materials may be used as long as the materials are able to withstand the subsequent steps of the process. When the semiconductor wafer 100 is disposed on the temporary carrier TC1 with the surface 100 a facing the carrier TC1, a backside surface 100 b of the semiconductor wafer 100 (opposite to the frontside surface 100 a) is exposed and available for further processing.

Referring to FIG. 1C, in certain embodiments, a first seed material layer 310 a is blanketly formed on the exposed backside surface 100 b of the semiconductor wafer 100. In some embodiments, the first seed material layer 310 a is formed directly on the exposed backside surface 100 b to be in direct contact with the semiconductor wafer 100. The first seed material layer 310 a may be formed through, for example, a sputtering process, a physical vapor deposition (PVD) process, or the like. In some embodiments, the first seed material layer 310 a includes, for example, copper, tantalum, titanium-copper alloys, or other suitable materials. In some embodiments, a barrier layer (not shown) may be deposited before forming the first seed material layer 310 a to prevent out-diffusion of the material of the first seed material layer 310 a.

In some embodiments, as shown in FIG. 1D, a first metal layer 320 a is formed over the first seed material layer 310 a. For example, the first metal layer 320 a may contain copper or other conductive metals, and may be formed by a plating technique such as electroplating or electroless plating, a sputtering process, or a PVD process. In one embodiment, a thickness of the first metal layer 320 a is in the range between 1 μm to 30 μm, and may be adjusted according to design requirements. As shown in FIG. 1D, in certain embodiments, the first metal layer 320 a blanketly covers the first seed material layer 310 a. In some alternative embodiments, the first metal layer 320 a is a patterned metal layer and partially covers the first seed material layer 320 a. As shown in FIG. 1D, in certain embodiments, after the first metal layer 320 a is formed, a first alloy layer 330 a is formed on the first metal layer 320 a. For example, the first alloy layer 330 a may be formed by a plating technique such as electroplating or electroless plating, a sputtering process, a PVD process, a printing process, or the like. In one embodiment, a thickness of the first alloy layer 330 a is in the range between 1 μm to 30 μm, and may be adjusted according to the design requirements. In some embodiments, the material of the first alloy layer 330 a includes eutectic solder containing lead or lead-free. In some embodiments, the material of the first alloy layer 330 a includes solder containing Sn—Ag, Sn—Cu, Sn—Ag—Cu, or similar soldering alloys. In some embodiments, the material of the first alloy layer 330 a includes non-eutectic solder. In the embodiments where the first metal layer 320 a is a patterned metal layer, the first alloy layer 330 a is a patterned layer having the same pattern as the first metal layer 320 a.

Referring to FIG. 1E and FIG. 1F simultaneously, following the formation of the first alloy layer 320 a, the semiconductor wafer 100 is overturned and placed on a carrier tape T, and, after detaching and removing the temporary carrier TC1, the protective glue G is removed from the semiconductor wafer 100, thereby exposing the passivation layer 116 and the first and second conductive vias 210, 220 for each semiconductor die 110. In some embodiments, as shown in FIG. 1F, a singulation step is performed to separate the individual dies 110, for example, by cutting through the semiconductor wafer 100 along the cut lines C1-C1 (shown in FIG. 1E) as well as cutting through the first seed material layer 310 a, the first metal layer 320 a and the first alloy layer 330 a. In the embodiments where the first metal layer 320 a and the first alloy layer 330 a are patterned layers, the singulation step is performed to cut through the semiconductor wafer 100 and the first seed material layer 310 a. In some embodiments, the singulation process typically involves performing a wafer dicing process with a rotating blade and/or a laser beam. In some embodiments, a wet cleaning step may be performed to remove residuals of the protective glue G before dicing the semiconductor wafer 100. After the singulation step, each die 110 may include a plurality of first conductive vias 210 and second conductive vias 220 connected to the conductive pads 114 on the top surface 110 a, and a first stacked layer 340 disposed on a rear surface 110 b opposite to the top surface 110 a. In some embodiments, the first stacked layer 340 includes a first seed layer 310, a first metal layer 320, and a first alloy layer 330 stacked in sequence from the rear surface 110 b. In certain embodiments, the first stacked layer 340 fully covers the whole rear surface 110 b of the die 110.

In FIG. 1G, a temporary carrier TC2 having a de-bonding layer DB formed thereon is provided. The temporary carrier TC2 may be made of the same materials as the temporary carrier TC1, and a detailed description thereof is omitted for brevity. In some embodiments, the de-bonding layer DB includes a light-to-heat conversion (LTHC) release layer, which facilitates peeling the temporary carrier TC2 away from the semiconductor package when required by the manufacturing process. In some embodiments, a second seed material layer 312 a is formed over the de-bonding layer DB. Formation of the second seed material layer may use similar processes and materials as previously described for the first seed material layer 310 a with reference to FIG. 1C, and a detailed description thereof is omitted herein. In some embodiments, the second seed material layer 312 a includes, for example, copper, tantalum, titanium-copper alloys, or other suitable materials.

Referring to FIG. 1H, a patterned photoresist PR1 is subsequently formed on the second seed material layer 312 a. In some embodiments, the patterned photoresist PR1 may include a plurality of openings OP1 exposing portions of the second seed material layer 312 a. In some embodiments, in FIG. 1H, each of the openings OP1 corresponds to a region where a semiconductor die (not shown) is to be placed (die attach location DA) in a subsequent step of the process. In some alternative embodiments, the patterned photoresist may expose only one or a few portions of each region where a die is to be disposed. In some embodiments, the patterned photoresist PR1 may be formed through exposure and development. In some embodiments, the region of the carrier where the semiconductor dies are going to be attached downstream along the process is neatly defined through photolithographic techniques. As such, the die attach locations are precisely defined and accuracy of the subsequent die attachment step can be increased.

Referring to FIG. 1I, a second metal layer 322 and a second alloy layer 332 are sequentially formed in the openings OP1 of the patterned photoresist PR1 and fill up the openings OP1 of the patterned photoresist PR1. The formation of the second metal layer 322 and the second alloy layer 332 may use the same or similar materials and formation methods of the first metal layer 320 a and the first alloy layer 330 a, respectively, and a detailed description thereof is omitted herein. In some embodiments, the second metal layer 322 may contain copper or other conductive metals. In some embodiments, the material of the second alloy layer 332 includes eutectic solder containing lead or lead-free. In some embodiments, the material of the second alloy layer 332 includes solder containing Sn—Ag, Sn—Cu, Sn—Ag—Cu, or similar soldering alloys. In some embodiments, the material of the second alloy layer 332 includes non-eutectic solder. In some embodiments, a thickness of the second metal layer 322 and a thickness of the second alloy layer 332 may be, independently of each other, in the range between 1 μm to 30 μm, but the disclosure is not limited thereto. The thickness of either layer 322, 332 may be adjusted according to design or performance requirements.

In FIG. 1J, the patterned photoresist PR1 is removed, for example by using a stripping solution or through an etching or ashing process, whereby the portions of the second seed material layer 312 a not covered by the second metal layer 322 are exposed. In some embodiments, the exposed portions of the second seed metal layer 312 a may be subsequently removed, for example via an etching process, to yield a patterned second seed layer 312 between the second metal layer 322 and the de-bonding layer DB. As shown in FIG. 1J, a second stacked layer 342 is formed in each die attach location DA, and the second stacked layer 342 includes a second seed layer 312, a second metal layer 322 and a second alloy layer 332 stacked in sequence on the de-bonding layer DB. In FIG. 1J, two die attach locations DA are shown and the second stacked layers 342 are disposed flanking each other on the de-bonding layer DB. It will be apparent to those of ordinary skill in the art that, whilst only two stacks of stacked layers are shown in FIG. 1J, several pairs of stacks or stacks in arrays can be formed simultaneously on the temporary carrier TC2. In other words, the steps of the disclosed methods can be performed in a parallel fashion to simultaneously produce a plurality of semiconductor packages 10 (shown in FIG. 1Q). A singulation step can be included after any stage of the method to produce individual semiconductor packages 10 or manufacturing intermediates thereof, according to the production requirements.

Referring to FIG. 1K and FIG. 2A simultaneously, a first semiconductor die 110C is disposed on one of the two stacks of the second stacked layers 342 and a second semiconductor die 110D is disposed on the other stack of the second stacked layers 342. In other words, in each die attach location DA, one semiconductor die is attached to each stack of second stacked layers 342. In some embodiments, the semiconductor dies 110C, 110D may be the same type of dies or perform the same functions. In some embodiments, the semiconductor dies 110C, 110D may be different types of dies or perform different functions. In some embodiments, the first semiconductor die 110C or the second semiconductor die 110D may be or include a logic die. The disclosure is not limited by the type of dies used for the semiconductor dies 110C, 110D. In some embodiments, the semiconductor dies 110C and 110D have been produced according to the method previously described with reference to FIGS. 1A-1F, and, as such, one or both of the dies 110C, 110D present the stack of first stacked layers 340 including the first seed layer 310, the first metal layer 320 and the first alloy layer 330 stacked on a rear surface 110 b thereof. In some embodiments, the semiconductor dies 110C, 110D are disposed on the temporary carrier TC2 in such a way that the stack of first stacked layers 340 of one semiconductor die is attached to one stack of the second stacked layers 342 in each die attach location DA. In certain embodiments, the first alloy layer 330 of each semiconductor die 110C or 110D faces the second alloy layer 332 of the corresponding underlying stack of second stacked layers 342, in a configuration where the stack of first stacked layer 340 is aligned with one stack of the second stacked layer 342. In some embodiments, the first die 110C and the second die 110D are arranged side by side and are so arranged that at least one first conductive via 210 of the first die 110C and one first conductive via 210 of the second die 110D form a pair of conductive vias that are most adjacent to each other (with the shortest horizontal distance between the two conductive vias of the pair). In some embodiments, the semiconductor dies 110C and 110D may be disposed in such a way that no second conductive via 220 is interposed between the first conductive via 210 of the first die 110C and the first conductive via 210 of the second die 110D, but the disclosure is not limited thereto.

In some embodiments, the dies 110C, 110D are placed on the temporary carrier TC2 by a pick and place process, and might be disposed in a somewhat misaligned manner with respect to the spans of the stacks of the second stacked layers 342. In other words, a pick and place process may introduce a shift between the intended position DA of the die and the position where each die 110C or 110D is effectively placed. In one embodiment, as shown in FIG. 2A, the intended positions of the dies DA are illustrated by the dashed lines (substantially the span of the stack of second stacked layers 342), and the placed position of the die 110C or 110D is illustrated as the dotted region (substantially the span of the stack of first stacked layers 340). In some embodiments of the present disclosure, after the pick and place process, the placed position of each die 110C or 110D may be shifted by about 1 μm with respect to the corresponding intended position DA.

Referring to FIG. 1L and FIG. 2B simultaneously, a reflow process is performed to join the first alloy layer 330 with the second alloy layer 332, thereby producing a joint alloy layer 334. The reflow temperature and the processing time of the reflow process can be optimized depending on the composition of the first alloy layer 330 and the second alloy layer 332. In some embodiments, intermetallic compounds or an intermetallic layer IM is formed in the joint alloy layer 334 by reflowing and joining together the adjacent two alloy layers. During the reflow process to form the joint alloy layer 334, the joining of the first alloy layer 330 with the second alloy layer 332 can make the first stacked layer 340 of the shifted semiconductor die 110C or 110D align with the underlying stack of the second stacked layer 342, improving the alignment between the semiconductor dies 110C, 110D and the corresponding stacks of the second stacked layers 342. As such, after the reflow process, a misalignment between the position of the stack of the second stacked layer 342 and the position of the overlying semiconductor die 110C or 110D may be further reduced. In some embodiments, reduction of the shift can be observed and the semiconductor dies are attached to the intended positions on the de-bonding layer DB in a self-aligned way even when an initial shift is about 1 μm. In some embodiments, as shown in FIG. 1L, the joint alloy layer 334 has side edges 334 s substantially aligned with side surfaces 110 s of the semiconductor dies 110C, 110D. In some embodiments the joint alloy layer 334 may somewhat protrude with respect to the side surface 110 s, depending on the amount of material used for the first 330 and second 332 alloy layers. In certain embodiments, the reflow process solders together the first stacked layers 340 on the rear surfaces 110 b of the semiconductor dies 110C, 110D with the corresponding stacks of the second stacked layers 342 formed on the temporary carrier TC2, thereby forming self-aligned structures 300. In other words, the self-aligned structure 300 attaches each semiconductor die 110C or 110D to the temporary carrier TC2. Furthermore, each self-aligned structure 300 at least partially corrects a shift in the position of each semiconductor die 110C or 110D that may have been introduced during the die placement step. Hence, better alignment of the die placement is achieved, which is beneficial for the packages with fine pitch or smaller form factors. In addition, the process window for the pick and place process is enlarged and higher throughput is achieved.

In some embodiments, the self-aligned structure 300 covers the entire rear surface 110 b of the semiconductor dies 110C, 110D, as shown in FIGS. 1L and 1 n FIG. 2B, but the disclosure is not limited thereto. In some alternative embodiments, the self-aligned structure 300 may be formed with the patterned first stacked layer 340 not covering the entire rear surface 110 b of the semiconductor die 110C or 110D. In some alternative embodiments, the self-aligned structure 300 may be formed with the patterned second stacked layer 342 not covering the entire span of the intended positions of the semiconductor dies 110C, 110D on the de-bonding layer DB. In some other embodiments, the self-aligned structure 300 may be formed with patterned first and second stacked layers 340, 342. As shown in FIGS. 2C and 2D, multiple self-aligned structures 300 may be formed for each semiconductor die 110C or 110D. The self-aligned structures 300C and 300D are shown as multiple square patches or multiple circular patches arranged within each die attach location (shown in dashed line), respectively, but the disclosure is not limited neither by the number nor by the shape of the self-aligned structures 300. In some embodiments, a coverage of the rear surface 110 b of each semiconductor die 110C or 110D by one or more self-aligned structures 300 is in the range from 5% to 100%.

In FIG. 1M, a bridge structure 400 is bonded to both of the first semiconductor die 110C and the second semiconductor die 110D, to establish electrical connection between the two semiconductor dies 110C and 110D. As shown in FIG. 1M, in some embodiments, the bridge structure 400 includes a semiconductor substrate 402, a dielectric layer 404 disposed on a bottom surface 402 b of the semiconductor substrate 402, and a conductive pattern 406 embedded in the dielectric layer 404. In some embodiments, the bridge structure 400 further includes through vias (e.g. through silicon vias) formed in the semiconductor substrate 402, establishing electrical connection between the bottom surface 402 b and an opposite top surface 402 t. In some embodiments, the bridge structure 400 electrically connects the two semiconductor dies 110C and 110D through their respective first conductive vias 210. In some embodiments, the bridge structure 400 further includes a plurality of connectors 410 disposed on a bottom surface 404 b of the dielectric layer 404 and connected to the conductive pattern 406. In some embodiments, the connectors 410 are micro-bumps containing copper posts and solder caps, but the disclosure is not limited thereto, and other conductive structures such as solder bumps, gold bumps or metallic bumps may also be used as the connectors 410. The connectors 410 may be bonded to the first conductive vias 210 through a reflow process. Upon bonding the bridge structure 400 to the semiconductor dies 110C, 110D, electrical connection between the semiconductor dies 110C and 110D is established through the first conductive vias 210, the connectors 410 and the conductive patterns 406. In some embodiments, the bridge structure 400 connects at least one first conductive via 210 of the first semiconductor die 110C with at least one first conductive via 210 of the second semiconductor die 110D. In some embodiments, the bridge structure 400 connects one or more first conductive vias 210 of the first semiconductor die 110C with one or more first conductive vias 210 of the second semiconductor die 110D. In some embodiments, where a gap G1 exists between the adjacent semiconductor dies 110C, 110D, the bridge structure 400 extends over such gap G1. In some embodiments, the bridge structure functions as an interconnecting structure for the semiconductor dies 110C, 110D and provides shorter electrical connection path between the two semiconductor dies 110C, 110D.

In FIG. 3A is shown a schematic top view of the manufacturing intermediate stage of FIG. 1M, whilst in FIG. 3B is shown an enlarged top view of the area A outlined in FIG. 3A. In some embodiments, because the formation of the self-aligned structure 300 (shown in FIG. 1M) corrected or improved at least partially a shift of the semiconductor dies 110C, 110D with respect to the originally intended positions, an alignment of the bridge structure 400 with the first conductive vias 210 is also improved. In some embodiments, the improved alignment of the bridge structure 400 with the first conductive vias 210 may increase the overlap between a horizontal section S₂₁₀ of a first conductive via 210 and a horizontal section S₄₁₀ of a connector 410. In some embodiments, a center C₂₁₀, C₄₁₀ of the horizontal sections S₂₁₀, S₄₁₀ is defined as the point minimizing the sum of the squared distances between the point itself and the outline (geometric center) of the corresponding horizontal section S₂₁₀, S₄₁₀. In some embodiments, the improved alignment of the bridge structure 400 with the first 110C and second 110D semiconductor dies may result in a significant reduction of a distance D_(cc) between the centers C₂₁₀ and C₄₁₀ of the horizontal sections S₂₁₀ and S₄₁₀. In some embodiments, the distance D_(cc) may be less than about 3 microns. As a non-limiting example, if the connectors 410 and the first conductive vias 210 have a cylindrical shape, the outline of the respective horizontal sections S₄₁₀, S₂₁₀ may be close to a circumference, and the center of each circumference may correspond to the center C₄₁₀, C₂₁₀ of the horizontal sections S₄₁₀, S₂₁₀. It will be apparent to the person skilled in the art that the above definition of center of a horizontal section can be applied to any shape of the first conductive vias 210 or of the connectors 410, and that the disclosure is not intended to be limited by the shape chosen for those components. As the shift of the die placement is minimized, better alignment and reliable connection of the bridge structure to the dies are attained, and the electrical performance of the package is enhanced.

Referring to FIG. 1N, an encapsulation material 500 a is formed over the temporary carrier TC2 to encapsulate the semiconductor dies 110C, 110D, the self-aligned structures 300, the bridge structure 400, the first conductive vias 210 and the second conductive vias 220. In some embodiments, the second conductive vias 220 and the bridge structure 400 are fully covered and not revealed by the encapsulation material 500 a. In some embodiments, the encapsulation material 500 a at least covers a side surface 300 s of the self-aligned structure, and may further fill the gap G1 between the semiconductor dies 110C, 110D. In some embodiments, the encapsulation material 500 a includes a molding compound, a molding underfill, a resin (such as an epoxy resin), or the like. In some embodiments, the encapsulation material 500 a is formed by an over-molding process. In some embodiments, the encapsulation material 500 a is formed by a compression molding process.

Referring to FIG. 1N and FIG. 1O, in some embodiments, the encapsulation material 500 a may be partially removed by a planarizing process until the top surface 400 t of the bridge structure 400 and the top surfaces 220 t of the second conductive vias 220 are exposed. In some embodiments, upper portions of the conductive vias 220 and/or an upper portion of the bridge structure 400 may also be removed during the planarizing process. Planarization of the encapsulation material 500 a may produce an encapsulant 500 located over the temporary carrier TC2 to encapsulate the conductive vias 210, 220, the semiconductor dies 110C, 110D, and the bridge structure 400. In some embodiments, the planarization of the encapsulation material 500 a and/or the bridge structure 400 includes performing a mechanical grinding process and/or a chemical mechanical polishing (CMP) process. After the grinding process or the polishing process, the top surfaces 220 t of the conductive vias 220 and the top surface 400 t of the bridge structure 400 may be substantially coplanar with a top surface 500 t of the encapsulant 500.

As shown in FIG. 1P, in some embodiments, a redistribution structure 600 is subsequently formed over the encapsulant 500, the second conductive vias 220 and the bridge structure 400. As shown in FIG. 1P, the redistribution structure 600 includes one or more dielectric layers 602, one or more conductive layers 604, and a plurality of interconnecting vias 606. Each conductive layer 604 may be constituted by a plurality of redistribution conductive patterns. For simplicity, the dielectric layer 602 is illustrated as one single dielectric layer, with the conductive layers 604 embedded therein. Nevertheless, from the perspective of the manufacturing process, the dielectric layer 602 is constituted by multiple dielectric layers and each conductive layer 604 is sandwiched between the two adjacent dielectric layers. As illustrated in FIG. 1P, the interconnecting vias 606 are also embedded in the dielectric layer 602. In some embodiments, materials of the conductive layer 604 and the interconnecting vias 606 include aluminum, titanium, copper, nickel, tungsten, and/or alloys thereof. The conductive layer 604 may be formed by, for example, electroplating, deposition, and/or photolithography and etching. In some embodiments, the material of the dielectric layer 602 includes polyimide, epoxy resin, acrylic resin, phenol resin, benzocyclobutene (BCB), polybenzoxazole (PBO), or any other suitable polymer-based dielectric material. The dielectric layer 602, for example, may be formed by suitable fabrication techniques such as spin-on coating, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or the like. It should be noted that the number of the conductive layers 604 and the number of the dielectric layers 602 may be adapted according to the design requirement, and do not constitute a limitation of the disclosure. In some alternative embodiments, more or fewer conductive layers and more or fewer dielectric layers may be formed depending on the circuit design.

Referring to FIG. 1P, at least a portion of the conductive vias 606 is exposed by a bottom surface 600 b of the redistribution structure 600, and is electrically connected to the second conductive vias 220. Furthermore, the redistribution structure 600 may present, on a top surface 600 t opposite to the bottom surface 600 b, a plurality of under bump metallurgies 608 electrically connected to at least a portion of the conductive layers 604. A plurality of connective terminals 700 is disposed on the under-bump metallurgies 608, through which is electrically connected to the redistribution structure 600. In some embodiments, the connective terminals 700 include solder balls. In some embodiments, the connective terminals 700 may be placed on the under-bump metallurgies 608 patterns through a ball placement process.

Referring to FIG. 1P, after the connective terminals 700 are formed on the redistribution structure 600, a singulation process is performed to dice the structure illustrated in FIG. 1P along the cut lines C2-C2 to form a plurality of semiconductor packages 10. In some embodiments, the singulation process involves performing a wafer dicing process with a rotating blade or a laser beam. In other words, the dicing or singulation process is a laser cutting process, a mechanical cutting process, or any other suitable process.

Referring to FIG. 1P and FIG. 1Q, the de-bonding layer DB and the temporary carrier TC2 are detached from the packages 10 and then removed, so that the surface of the self-aligned structure 300 is exposed. In some embodiments, the de-bonding layer DB (e.g., the LTHC release layer) is irradiated with a UV laser so that the carrier TC2 and the de-bonding layer DB are easily peeled off from the packages 10. Nevertheless, the de-bonding process is not limited thereto, and other suitable de-bonding methods may be used in some alternative embodiments.

Based on the above, in some embodiments, a semiconductor package 10 includes a first 110C and a second 110D semiconductor dies bearing a plurality of first conductive vias 210 interconnected through a bridge structure 400, and a plurality of second conductive vias 220 establishing electrical connection with a redistribution structure 600. A self-aligned structure 300 is built on the rear surface 110 b of each die 110C or 110D. In some embodiments, the self-aligned structure is formed by joining together a first stacked layer 340 formed on the rear surface 110 b of each semiconductor die 110C or 110D, to a second stacked layer 342. The stacked layer 340 includes a seed layer 310, a metal layer 320 and an alloy layer 330. The stacked layer 342 includes a seed layer 312, a metal layer 322 and an alloy layer 332. In some embodiments, the self-aligned structure 300 is formed by soldering the two alloy layers 330, 332 to produce a joint alloy layer. The first conductive vias 210, the second conductive vias 220, the first semiconductor die 110C, the second semiconductor die 110D, the self-aligned structure 300, and the bridge structure 400 are enclosed by the encapsulant 500. A redistribution structure 600 is formed over the encapsulant 500 and is electrically connected to the second conductive vias 220, and a plurality of connective terminals 700 is located on and electrically connected with the redistribution structure 600.

As shown in FIG. 1R, the package structure 10 may be mounted and bonded to a circuit carrier 1000, such as a printed circuit board, a mother board, or the like.

In alternative embodiments, after bonding the bridge structure, forming the encapsulant and removing the temporary carrier, the exposed self-aligned structures may be removed or further mounted with other components or devices, depending on the product requirements. Because possible shifts during the placement of the individual semiconductor dies have been lessened or corrected through the formation of the self-aligned structures, better alignment of the bridge structure with the semiconductor dies is still achieved even subsequently removing the self-aligned structure from the packages.

In FIG. 4A is shown a schematic cross-sectional view of a semiconductor package 15 according to some embodiments of the present disclosure. The semiconductor package 15 of FIG. 4A may contain similar components to the semiconductor package 10 of FIG. 1R, and the same or similar reference numerals are used to indicate analogous components between the two packages 10 and 15. The semiconductor package 15 differs from the semiconductor package 10 as including a heat spreading module 800 connected to the self-aligned structures 300 and the encapsulant 500. In some embodiments, the heat spreading module 800 is attached to the self-aligned structures 300 and the encapsulant 500 by a thermal interface material layer (not shown), an adhesive (not shown), or a combination thereof. In some embodiments, the heat spreading module 800 consists of a block of thermally conductive material that promotes dissipation of the heat produced while operating the semiconductor dies 110C, 110D. In some embodiments, the heat spreading module 800 is a laminated structure comprising a plurality of different metallic or thermally conductive layers.

In FIG. 4B is shown a schematic cross-sectional view of a semiconductor package 20 according to some embodiments of the present disclosure. The semiconductor package 20 is similar to the semiconductor package 10, and the same or similar parts have been indicated with the same or similar reference numbers in the two packages. As shown in FIG. 4B, in some embodiments, the semiconductor package 20 includes the first conductive vias 210 formed also on the conductive pads 114 further away from the periphery of the die. As such, the bridge structure 400 in the semiconductor package 20 includes nested conductive patterns 406A, 408B to reach on both the peripheral first conductive vias 210A, and the non-peripheral first conductive vias 210B. That is, the bridge structure 400 not only connects the most adjacent first conductive vias 210A but also connects other first conductive vias 210B located farther away from the gap between the two adjacent dies 110C, 110D.

FIG. 5A through FIG. 5G are schematic cross-sectional views illustrating structures produced at various stages of a manufacturing method of a semiconductor package 30 shown in FIG. 5G.

In FIG. 5A is shown a cross-sectional view of a manufacturing intermediate produced following similar steps as previously discussed with reference to FIGS. 1B-1L. Briefly, two semiconductor dies 120C, 120D are provided. Each semiconductor dies 120C or 120D includes a semiconductor substrate 122 having a plurality of conductive pads 124 formed on a top surface 122 t of the semiconductor substrate 122, a passivation layer 126 covering the top surface 122 t and having a plurality of openings that exposes at least a portion of each conductive pad 124, a plurality of conductive posts 128 filling the openings of the passivation layer 126, and a protective layer 130 surrounding the conductive posts 128. On a rear surface 120 b of each semiconductor die 120C or 120D is formed a first stacked layer 340 including a first seed layer 310, a first metal layer 320 and a first alloy layer 330. The two semiconductor dies 120C, 120D are placed on the die attach regions DA of a temporary carrier TC3 bearing a de-bonding layer DB3 and having a second stacked layers 342 formed on each die attach region DA. The second stacked layer 342 includes a second seed layer 312, a second metal layer 322, and a second alloy layer 332. As described with reference to FIG. 1K, the two semiconductor dies 120C, 120D may be disposed on the temporary carrier TC3 via a pick and place process.

Referring to FIG. 5B, a self-aligned structure 300 is formed on the rear surface 120 b of each die 120C or 120D by soldering together the first alloy layer 330 and the second alloy layer 332 to form a joint alloy layer 334. The formation of the self-aligned structure 300 may correct for shifts in the original placement positions of the two semiconductor dies 120C, 120D with respect to the die attach locations DA. After the self-aligned structures 300 are formed, the two semiconductor dies 120C, 120D and the self-aligned structures 300 are encapsulated in an encapsulant 500. The encapsulant 500 may be formed by a sequence of over-molding and grinding, as described above with reference to FIG. 1N and FIG. 1O. A top surface 500 t of the encapsulant 500 may expose a top surface 120 t of each semiconductor die 120C or 120D. The top surface 120 t may be defined by the top surfaces of the conductive posts 128 and the top surface of the protective layer 130. In some embodiments, during the grinding step performed to form the encapsulant 500, upper portions of the conductive posts 128 and the protective layer 130 may also be removed.

Referring to FIG. 5C, after forming the encapsulant 500, a patterned protective layer 230 is formed on the top surface 500 t of the encapsulant 500 and the top surfaces 120 t of the semiconductor dies 120C, 120D. The patterned protective layer 230 may expose at least a portion of the conductive posts 128 of each die 120C or 120D. In some embodiments, a material of the patterned protective layer 230 includes polyimide, epoxy resin, acrylic resin, phenol resin, benzocyclobutene (BCB), polybenzoxazole (PBO), or any other suitable polymer-based dielectric material. The patterned protective layer 230 may be formed by suitable fabrication techniques such as spin-on coating, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or the like. In some embodiments, the pattern of the patterned dielectric layer 230 may be produced during an etching step.

In some embodiments, as shown in FIG. 5C, a plurality of conductive through vias 250 is formed on at least some of the conductive posts 128 of each die 120C or 120D. In some embodiments, the conductive through vias 250 include through interlayer vias (TIVs). A material of the conductive through vias 250 may contain copper, copper alloys, or the like. A third seed layer 240 may be disposed between the conductive through vias 250 and the conductive posts 128. A portion of the seed layer 240 may further extend between the conductive through vias 250 and an underlying portion of the patterned protective layer 230. Formation of the conductive through vias 250 may involve the following steps. First a blanket third seed material layer (not shown) is deposited, covering the entire patterned protective layer 230. A patterned mask (not shown) is then produced, for example through a sequence of deposition, photolithography, and etching. The patterned mask (not shown) exposes through a plurality of openings (not shown) portions of the third seed material layer overlying the conductive bumps 128. Filling of the openings of the patterned mask with a conductive material (not shown) and subsequent removal of the patterned mask and the underlying portions of the third seed material layer produces the third seed layer 240 and the conductive through vias 250. In some embodiments, at least one conductive post 128 for each semiconductor die 120C or 120D is covered by the patterned mask (not shown), so that a conductive through via 250 is not formed thereon. Upon removal of the patterned mask (not shown), the conductive posts 128 on which no conductive through vias 250 were formed are again exposed by the openings of the patterned protective layer 230.

Referring to FIG. 5D, in a subsequent step of the process a bridge structure 400 is bonded to the exposed conductive posts 128, similarly to what described above with reference to FIG. 1M. In some embodiments, the bridge structure 400 is electrically connected to the conductive posts 128 of each die 120C or 120D through a plurality of conductors 410. In some embodiments, because shifts in the placement position of each semiconductor die 120C or 120D were at least partially corrected during formation of the self-aligned structures 300, a degree of alignment of the bridge structure 400 with the semiconductor dies 120C, 120D is increased, and a more reliable connection is established.

Referring to FIG. 5E, an underfill 430 may be optionally produced between the bridge structure 400 and the patterned protective layer 230 to protect the connectors 410. The conductive through vias 250 and the bridge structure 400 are then encapsulated in a second encapsulant 510 formed over the patterned protective layer 230. The second encapsulant 510 may be formed following similar processes and using similar materials as described for the encapsulant 500, and a detailed description thereof is omitted herein. If a grinding process is performed, a portion of the bridge structure 400 and a portion of each conductive through via 250 may also be removed. A redistribution structure 600 is further formed on top of the second encapsulant 510, the conductive through vias 250 and the bridge structure 400. The redistribution structure 600 is electrically connected to each semiconductor die 120C or 120D through the conductive through vias 250. The redistribution structure 600 is further connected to the bridge structure 400 through the semiconductor dies 120C and 120D. A plurality of connective terminals 700 is connected to the redistribution structure, and may be used to integrate the produced semiconductor package into larger devices (not shown).

Referring to FIG. 5F, a singulation step is performed by dicing along the cut lines C3-C3 (shown in FIG. 5F), similarly to the steps described above with reference to FIG. 1P, and the temporary carrier TC3 and the de-bonding layer DB3 are detached from the package array.

Based on the above, a semiconductor package 30 shown in FIG. 5G includes the first semiconductor die 120C and the second semiconductor die 120D interconnected through the bridge structure 400. The conductive through vias 250 establishes electrical connection between the semiconductor dies 120C, 120D and the redistribution structure 600. In some embodiments, the self-aligned structures 300 are built on the rear surfaces 120 b of each die 120C or 120D. Each self-aligned structure 300 is formed by joining together a first stacked layer 340 formed on a rear surface 120 b of each semiconductor die 120C or 120D, with a second stacked layer 342. In some embodiments, the stacked layer 340 includes a seed layer 310, a metal layer 320 and an alloy layer 330, while the stacked layer 342 includes a seed layer 312, a metal layer 322 and an alloy layer 332. In certain embodiments, the self-aligned structure 300 is formed by soldering the two alloy layers 330, 332 into a joint alloy layer 334. The first semiconductor die 120C, the second semiconductor die 120D and the self-aligned structures 300 are encapsulated by the encapsulant 500. The patterned protective layer 230 is formed over the encapsulant 500. The second encapsulant 510 is disposed over the dielectric layer 230 and encapsulates the bridge structure 400 and the conductive through vias 250. The redistribution structure 600 is electrically connected to the conductive through vias 250 and to the connective terminals 700.

In FIG. 6 is shown a schematic cross-sectional view of a semiconductor package 40 according to some embodiments of the present disclosure. The semiconductor package 40 of FIG. 6 may contain similar components to the semiconductor package 30 of FIG. 5G, and the same or similar reference numerals are used to indicate analogous elements or components. The semiconductor package 40 differs from the semiconductor package 30 as a bridge structure 400B interconnecting the semiconductor dies 120C, 120D comprises at least one through interconnection via 408 formed in the semiconductor substrate 402. In other words, the bridge structure 400B provides horizontal integration between the two semiconductor dies 120C, 120D, and also vertical electrical connection between the semiconductor dies 120C, 120D and the redistribution structure 600. As shown in FIG. 6, at least some of the interconnecting vias 606 of the redistribution structure are connected to the through interconnection vias 408 formed in the bridge structure 400B. To achieve vertical electrical connection, the conductive pattern 406C embedded in the dielectric layer 404 of the bridge structure 400B extend through an entire thickness direction of the dielectric layer 404, contacting the connectors 410 and the through interconnection vias 408.

In some embodiments, as shown in FIG. 6, the protective layer 230 may cover only partially the semiconductor dies 120C, 120D and not extend over the portion of the encapsulant 500 filling the gap G in between the two semiconductor dies 120C and 120D. As such, the conductive posts 128 of each semiconductor die 120C, 120D that are connected through the bridge structure 400B are exposed by the same opening of the protective layer 230. In some embodiments, the underfill 430 may fill the larger opening of the protective layer 230 and contact the semiconductor dies 120C, 120D.

In light of the present disclosure, formation of a self-aligned structure on the rear surface of the semiconductor dies after placement of the dies on a carrier ensures a closer final position of the dies to the originally intended position. In other words, placement shift possibly introduced by pick and place methods used to deposit the dies on the carrier can be at least partially corrected. As such, an alignment between the semiconductor dies and a bridge structure interconnecting the semiconductor dies is improved, ensuring a more robust electrical connection. As such, reliability of the semiconductor package is increased, and a failure rate due to alignment issues may also be reduced. In some embodiments the self-aligned structure may also help to dissipate the heat generated by the semiconductor dies during the use of the semiconductor package, or may serve as a connection between the package and a heat dissipating module.

In some embodiments of the present disclosure, a semiconductor package includes a first chip, a second chip, self-aligned structures, a bridge structure, and an insulating encapsulant. The first chip has a first active surface, a first rear surface opposite to the first active surface and a first plurality of conductive pads disposed on the first active surface. The second chip is disposed beside the first chip and has a second active surface, a second rear surface opposite to the second active surface and a second plurality of conductive pads disposed on the second active surface. The self-aligned structures are respectively disposed on the first rear surface of the first chip and the second rear surface of the second chip. The bridge structure has a semiconductor substrate. The bridge structure is electrically connected to at least one conductive pad of the first chip and at least one conductive pad of the second chip. The insulating encapsulant covers at least the side surfaces of the first and second chips, a side surface of the semiconductor substrate, and the side surfaces of the self-aligned structures.

In some embodiments of the present disclosure, a semiconductor package includes a pair of semiconductor dies, and each of the pair of semiconductor dies has conductive pads disposed on an active surface. A bridge structure is also included in the semiconductor package. The bridge structure is connected to at least one conductive pad of one of the pair of semiconductor dies and at least one conductive pad of the other of the pair of semiconductor dies. The semiconductor package further includes a multilayered structure disposed on a rear surface of each of the pair of semiconductor dies. At least one multilayered structure includes a top metal layer, a bottom metal layer, and an intermetallic layer and has a surface coplanar with a surface of the insulating encapsulant. An insulating encapsulant surrounds the bridge structure and the multilayered structures and encapsulates the pair of semiconductor dies.

In some embodiments of the present disclosure, a manufacturing method of a semiconductor package includes at least the following steps. A chip is provided. The chip has an active surface and a rear surface opposite to the active surface. The chip includes conductive pads disposed at the active surface. A first solder-containing alloy layer is formed on the rear surface of the chip. A second solder-containing alloy layer is formed on a surface and at a location where the chip is to be attached. The chip is mounted to the surface and the first solder-containing alloy layer is aligned with the second solder-containing alloy layer. A reflow step is performed on the first and second solder-containing alloy layers to form a joint alloy layer between the chip and the surface.

In some embodiments of the present disclosure, a manufacturing method of a semiconductor package includes at least the following steps. A pair of first metal layers is formed side by side on a carrier. First solder layers are formed on the first metal layers of the pair. A pair of semiconductor dies is disposed on the carrier. Second metal layers and second solder layers are stacked, in order, on rear surfaces of the semiconductor dies of the pair of semiconductor dies. The pair of semiconductor dies is disposed on the carrier so that the second solder layer formed on a first semiconductor die of the pair of semiconductor dies contacts the first solder layer formed on one first metal layer of the pair of first metal layers, and the second solder layer formed on the second semiconductor die of the pair of semiconductor dies contacts the first solder layer formed on the other first metal layer of the pair of first metal layers. The second solder layers to the first solder layers are soldered together by heating.

In some embodiments of the present disclosure, a manufacturing method of a semiconductor package includes at least the following steps. First stacks of metallic layers are formed on rear surfaces of semiconductor dies. Second stacks of metallic layers are formed on a surface on which the semiconductor dies are to be attached. The semiconductor dies are disposed on the surface on which the semiconductor dies are to be attached with the first stacks contacting the second stacks. The first stacks and the second stacks are reflowed to attach the semiconductor dies to the surface.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents. 

What is claimed is:
 1. A manufacturing method of a semiconductor package, comprising: providing a chip having an active surface and a rear surface opposite to the active surface, wherein the chip comprises conductive pads disposed at the active surface; forming a first solder-containing alloy layer on the rear surface of the chip; forming a second solder-containing alloy layer on a surface and at a location where the chip is to be attached; mounting the chip to the surface and aligning the first solder-containing alloy layer with the second solder-containing alloy layer; and reflowing the first and second solder-containing alloy layers to form a joint alloy layer between the chip and the surface.
 2. The manufacturing method of claim 1, wherein the first solder-containing alloy layer is formed on the rear surface of the chip to cover a portion of the rear surface.
 3. The manufacturing method of claim 1, wherein the first solder-containing alloy layer is formed on the rear surface of the chip to cover the whole rear surface.
 4. The manufacturing method of claim 1, further comprising forming a first metallic layer on the rear surface of the chip before forming the first solder-containing alloy layer.
 5. The manufacturing method of claim 4, further comprising forming a second metallic layer on the surface and at the location where the chip is to be attached before forming the second solder-containing alloy layer.
 6. The manufacturing method of claim 5, further comprising: mounting another chip to the surface by forming another joint alloy layer between the other chip and the surface; and bonding a bridge structure to the chip and the other chip, wherein the bridge structure physically connects the chip and the other chip and electrically connects the chip with the other chip.
 7. The manufacturing method of claim 6, further comprising: forming an encapsulating material that completely covers the bridge structure; and thinning the encapsulating material to form an encapsulant, whereby a top surface of the encapsulant is coplanar with a top surface of the bridge structure.
 8. A manufacturing method of a semiconductor package, comprising: forming a pair of first metal layers side by side on a carrier; forming first solder layers on the first metal layers of the pair; disposing a pair of semiconductor dies on the carrier, wherein second metal layers and second solder layers are stacked, in order, on rear surfaces of the semiconductor dies of the pair of semiconductor dies, and the pair of semiconductor dies is disposed on the carrier so that the second solder layer formed on a first semiconductor die of the pair of semiconductor dies contacts the first solder layer formed on one first metal layer of the pair of first metal layers, and the second solder layer formed on the second semiconductor die of the pair of semiconductor dies contacts the first solder layer formed on the other first metal layer of the pair of first metal layers; and soldering together by heating the second solder layers to the first solder layers.
 9. The manufacturing method of claim 8, wherein forming the pair of first metal layers comprises: blanketly forming a seed material layer on the carrier; patterning a photoresist on the seed material layer, wherein the patterned photoresist includes openings exposing the seed material layer; and disposing a metal material of the first metal layers in the openings of the patterned photoresist.
 10. The manufacturing method of claim 9, wherein forming the first solder layers comprises disposing a solder material on the metal material in the openings of the patterned photoresist.
 11. The manufacturing method of claim 8, further comprising bonding a semiconductor bridge to the pair of semiconductor dies after the first solder layers and the second solder layers are soldered together, wherein the semiconductor bridge comprises a first conductive bump connected to the first semiconductor die and a second conductive bump connected to the second semiconductor die.
 12. The manufacturing method of claim 8, further comprising: disposing a metal material on a rear surface of a semiconductor wafer to form a blanket metal layer, wherein a region of the semiconductor wafer corresponds to the first semiconductor die; disposing a solder material on the blanket metal layer to form a blanket solder layer; and cutting through the semiconductor wafer, the blanket metal layer, and the blanket solder layer to obtain the first semiconductor die having the second metal layer and the second solder layer formed on the rear surface.
 13. The manufacturing method of claim 12, further comprising forming conductive vias on a front surface of the semiconductor wafer, wherein, in the region of the semiconductor wafer corresponding to the first semiconductor die, at least one conductive via of the conductive vias is formed to be shorter than the other conductive vias.
 14. The manufacturing method of claim 13, further comprising bonding a conductive bump of a semiconductor bridge to the shorter conductive via of the first semiconductor die after the first semiconductor die is soldered to the carrier.
 15. A manufacturing method of a semiconductor package, comprising: forming first stacks of metallic layers on rear surfaces of semiconductor dies; forming second stacks of metallic layers on a surface on which the semiconductor dies are to be attached; disposing the semiconductor dies on the surface on which the semiconductor dies are to be attached with the first stacks contacting the second stacks; and reflowing the first stacks and the second stacks to attach the semiconductor dies to the surface.
 16. The manufacturing method of claim 15, further comprising bonding a bridge structure to front surfaces of two semiconductor dies of the semiconductor dies after the semiconductor dies are attached to the surface, wherein the bridge structure includes a conductive pattern electrically interconnecting the two semiconductor dies.
 17. The manufacturing method of claim 16, further comprising: encapsulating the semiconductor dies and the joined stacks in an encapsulant after the semiconductor dies are attached to the surface; and forming conductive vias on front surfaces of the semiconductor dies.
 18. The manufacturing method of claim 17, wherein the semiconductor dies are encapsulated after the bridge structure is bonded to the two semiconductor dies, and the encapsulant further encapsulates the bridge structure and the conductive vias.
 19. The manufacturing method of claim 17, further comprising forming a patterned protective layer on the encapsulated semiconductor dies, wherein the patterned protective layer includes a plurality of openings and the conductive vias are formed in the openings of the patterned protective layer; and forming another encapsulant on the patterned protective layer, wherein the other encapsulant encapsulates the bridge structure and the conductive vias.
 20. The manufacturing method of claim 15, wherein the first stacks include first solder layers, the second stacks include second solder layers, and joint alloy layers including an intermetallic compound are formed from the first solder layers and the second solder layers during the reflowing step. 